I. Technical Field
The present invention relates to a coupling member for a pipe coupling, and more particularly, to a coupling member including an inner valve seat member disposed in the radially central portion of a cylindrical coupling body, an outer valve seat member disposed on an inner peripheral surface of the coupling body at a position corresponding to that of the inner valve seat member, and a cylindrical or annular valve member disposed in the coupling body and being displaceable in an axial direction between a closed position where the valve member engages with the inner and outer valve members to close a fluid passage of the coupling body and an open position where the valve member is apart from the inner and outer valve members to open the fluid passage.
II. Description of the Related Art
Male and female coupling members for a pipe coupling are generally provided, in a cylindrical coupling body thereof, with a valve device for opening and closing a fluid passage. There are various types of valve devices. One example is a valve device in which a cylindrical valve member is slidable along an inner peripheral surface of the coupling body, a valve seat member is disposed at the radially central position of the cylindrical body, and the valve member sealingly engages with the valve seat member to close the fluid passage when the valve member is at a fluid passage closed position. In this type of coupling member, a sealing member such as an O-ring is disposed between an outer peripheral surface of the valve member and the inner peripheral surface of the cylindrical body, thereby preventing a fluid from leaking from a gap between the male and female members (for example, U.S. Pat. No. 4,936,345). In another example, instead of using a sealing member, a valve member itself is formed of rubber or the like to also to be adapted as a sealing member (for example, Japanese Unexamined Utility Model Registration Application Publication No. 64-49791).